[PATCH 1/4] video: Add support for the Solomon SSD1307 OLED Controller

Hello Maxim,

On Tue, Jul 31, 2012 at 3:59 PM, Maxime Ripard <
maxime.ripard@free-electrons.com> wrote:

Why cant we just return from here with -ENOMEM directly rather than jumping
to a label, which again just returns?

+       }
+
+       buf[0] = type;
+       memcpy(buf + 1, cmd, len);
+
+       ret = i2c_master_send(client, buf, len + 1);
+       if (ret != len + 1) {
+               dev_err(&client->dev, "Couldn't send I2C command.\n");
+               goto error;
+       }
+
+error:
+       kfree(buf);
+out:
+       return ret;
+}
+
+static inline int ssd1307fb_write_cmd_array(struct i2c_client *client,
u8* cmd, u32 len)
+{
+       return ssd1307fb_write_array(client, SSD1307FB_COMMAND, cmd, len);
+}
+
+static inline int ssd1307fb_write_cmd(struct i2c_client *client, u8 cmd)
+{
+       return ssd1307fb_write_cmd_array(client, &cmd, 1);
+}
+
+static inline int ssd1307fb_write_data_array(struct i2c_client *client,
u8* cmd, u32 len)
+{
+       return ssd1307fb_write_array(client, SSD1307FB_DATA, cmd, len);
+}
+
+static inline int ssd1307fb_write_data(struct i2c_client *client, u8 data)
+{
+       return ssd1307fb_write_data_array(client, &data, 1);
+}
+
+static int ssd1307fb_set(struct i2c_client *client, u8 value)
+{
+       int i, j, ret;
+
+       for (i = 1; i <= (SSD1307FB_HEIGHT / 8); i++) {
+               ret = ssd1307fb_write_cmd(client,
SSD1307FB_START_PAGE_ADDRESS + i);
+               if (ret < 0)
+                       goto i2c_error;
+
+               ret = ssd1307fb_write_cmd(client, 0x00);
+               if (ret < 0)
+                       goto i2c_error;
+
+               ret = ssd1307fb_write_cmd(client, 0x10);
+               if (ret < 0)
+                       goto i2c_error;
+
+               for (j = 0; j < SSD1307FB_WIDTH; j++)
+                       ssd1307fb_write_data(client, value);
+       }
+
+       return 0;
+
+i2c_error:
+       dev_err(&client->dev, "Couldn't send i2c command: %d\n", ret);
+       return ret;
+}
+
+static void ssd1307fb_update_display(struct ssd1307fb_par *par)
+{
+       u8 *vmem = par->info->screen_base;
+       int i, j, k;
+
+       /*
+        * The screen is divided in pages, each having a height of 8
+        * pixels, and the width of the screen. When sending a byte of
+        * data to the controller, it gives the 8 bits for the current
+        * column. I.e, the first byte are the 8 bits of the first
+        * column, then the 8 bits for the second column, etc.
+        *
+        *
+        * Representation of the screen, assuming it is 5 bits
+        * wide. Each letter-number combination is a bit that controls
+        * one pixel.
+        *
+        * A0 A1 A2 A3 A4
+        * B0 B1 B2 B3 B4
+        * C0 C1 C2 C3 C4
+        * D0 D1 D2 D3 D4
+        * E0 E1 E2 E3 E4
+        * F0 F1 F2 F3 F4
+        * G0 G1 G2 G3 G4
+        * H0 H1 H2 H3 H4
+        *
+        * If you want to update this screen, you need to send 5 bytes:
+        *  (1) A0 B0 C0 D0 E0 F0 G0 H0
+        *  (2) A1 B1 C1 D1 E1 F1 G1 H1
+        *  (3) A2 B2 C2 D2 E2 F2 G2 H2
+        *  (4) A3 B3 C3 D3 E3 F3 G3 H3
+        *  (5) A4 B4 C4 D4 E4 F4 G4 H4
+        */
+
+       for (i = 0; i < (SSD1307FB_HEIGHT / 8); i++) {
+               ssd1307fb_write_cmd(par->client,
SSD1307FB_START_PAGE_ADDRESS + (i + 1));
+               ssd1307fb_write_cmd(par->client, 0x00);
+               ssd1307fb_write_cmd(par->client, 0x10);
+
+               for (j = 0; j < SSD1307FB_WIDTH; j++) {
+                       u8 buf = 0;
+                       for (k = 0; k < 8; k++) {
+                               u32 page_length = SSD1307FB_WIDTH * i;
+                               u32 index = page_length + (SSD1307FB_WIDTH
* k + j) / 8;
+                               u8 byte = *(vmem + index);
+                               u8 bit = byte & (1 << (7 - (j % 8)));
+                               bit = bit >> (7 - (j % 8));
+                               buf |= bit << k;
+                       }
+                       ssd1307fb_write_data(par->client, buf);
+               }
+       }
+
+       return;

'return' not required?

+}
+
+
+static ssize_t ssd1307fb_write(struct fb_info *info, const char __user
*buf,
+               size_t count, loff_t *ppos)
+{
+       struct ssd1307fb_par *par = info->par;
+       unsigned long p = *ppos;
+       void *dst;
+       int err = 0;
+
+       dst = (void __force *) (info->screen_base + p);
+
+       if (copy_from_user(dst, buf, count))
+               err = -EFAULT;
+
+       if  (!err)
+               *ppos += count;
+
+       ssd1307fb_update_display(par);
+
+       return (err) ? err : count;
+}
+
+static void ssd1307fb_fillrect(struct fb_info *info, const struct
fb_fillrect *rect)
+{
+       struct ssd1307fb_par *par = info->par;
+       sys_fillrect(info, rect);
+       ssd1307fb_update_display(par);
+}
+
+static void ssd1307fb_copyarea(struct fb_info *info, const struct
fb_copyarea *area)
+{
+       struct ssd1307fb_par *par = info->par;
+       sys_copyarea(info, area);
+       ssd1307fb_update_display(par);
+}
+
+static void ssd1307fb_imageblit(struct fb_info *info, const struct
fb_image *image)
+{
+       struct ssd1307fb_par *par = info->par;
+       sys_imageblit(info, image);
+       ssd1307fb_update_display(par);
+}
+
+static struct fb_ops ssd1307fb_ops = {
+       .owner          = THIS_MODULE,
+       .fb_read        = fb_sys_read,
+       .fb_write       = ssd1307fb_write,
+       .fb_fillrect    = ssd1307fb_fillrect,
+       .fb_copyarea    = ssd1307fb_copyarea,
+       .fb_imageblit   = ssd1307fb_imageblit,
+};
+
+static void ssd1307fb_deferred_io(struct fb_info *info,
+                               struct list_head *pagelist)
+{
+       ssd1307fb_update_display(info->par);
+}
+
+static struct fb_deferred_io ssd1307fb_defio = {
+       .delay          = HZ,
+       .deferred_io    = ssd1307fb_deferred_io,
+};
+
+static int __devinit ssd1307fb_probe(struct i2c_client *client, const
struct i2c_device_id *id)
+{
+       struct fb_info *info;
+       u32 vmem_size = SSD1307FB_WIDTH * SSD1307FB_HEIGHT / 8;
+       struct ssd1307fb_par *par;
+       u8 *vmem;
+       int ret;
+
+       if (!client->dev.of_node) {
+               dev_err(&client->dev, "No device tree data found!\n");
+               ret = -EINVAL;
+               goto generic_error;

Again, can just return from here with the error value...

+       }
+
+       info = framebuffer_alloc(sizeof(struct ssd1307fb_par),
&client->dev);
+       if (!info) {
+               ret = -ENOMEM;
+               goto generic_error;

ditto

+       }
+
+       vmem = devm_kzalloc(&client->dev, vmem_size, GFP_KERNEL);
+       if (!vmem) {
+               dev_err(&client->dev, "Couldn't allocate graphical
memory.\n");
+               ret = -ENOMEM;
+               goto generic_error;

ditto

+       }
+
+       info->fbops = &ssd1307fb_ops;
+       info->fix = ssd1307fb_fix;
+       info->fbdefio = &ssd1307fb_defio;
+
+       info->var = ssd1307fb_var;
+       info->var.red.length = 1;
+       info->var.red.offset = 0;
+       info->var.green.length = 1;
+       info->var.green.offset = 0;
+       info->var.blue.length = 1;
+       info->var.blue.offset = 0;
+
+       info->screen_base = (u8 __force __iomem *)vmem;
+       info->fix.smem_start = (unsigned long)vmem;
+       info->fix.smem_len = vmem_size;
+
+       fb_deferred_io_init(info);
+
+       par = info->par;
+       par->info = info;
+       par->client = client;
+
+       par->reset = of_get_named_gpio(client->dev.of_node,
+                                        "oled-reset-gpio", 0);
+       if (gpio_is_valid(par->reset)) {
+               int flags = GPIOF_OUT_INIT_HIGH;
+               if (of_get_property(client->dev.of_node,
+                                   "oled-reset-active-low", NULL))
+                       flags = GPIOF_OUT_INIT_LOW;
+               ret = devm_gpio_request_one(&client->dev, par->reset,
+                                           flags, "oled-reset");
+               if (ret) {
+                       dev_err(&client->dev,
+                               "failed to request gpio %d: %d\n",
+                               par->reset, ret);
+                       goto reset_oled_error;
+               }
+       }
+
+       par->pwm = pwm_get(&client->dev, NULL);
+       if (IS_ERR(par->pwm)) {
+               dev_err(&client->dev, "Could not get PWM from device
tree!\n");
+               ret = PTR_ERR(par->pwm);
+               goto pwm_error;
+       }
+
+       par->pwm_period = pwm_get_period(par->pwm);
+
+       dev_dbg(&client->dev, "Using PWM%d with a %dns period.\n",
par->pwm->pwm, par->pwm_period);
+
+       ret = register_framebuffer(info);
+       if (ret) {
+               dev_err(&client->dev, "Couldn't register the
framebuffer\n");
+               goto fbreg_error;
+       }
+
+       i2c_set_clientdata(client, info);
+
+       /* Reset the screen */
+       gpio_set_value(par->reset, 1);
+       udelay(4);
+       gpio_set_value(par->reset, 0);
+       udelay(4);
+
+       /* Enable the PWM */
+       pwm_config(par->pwm, par->pwm_period / 2, par->pwm_period);
+       pwm_enable(par->pwm);
+
+       /* Map column 127 of the OLED to segment 0 */
+       ret = ssd1307fb_write_cmd(client, SSD1307FB_SEG_REMAP_ON);
+       if (ret < 0) {
+               dev_err(&client->dev, "Couldn't remap the screen.\n");
+               goto remap_error;
+       }
+
+       /* Turn on the display */
+       ret = ssd1307fb_write_cmd(client, SSD1307FB_DISPLAY_ON);
+       if (ret < 0) {
+               dev_err(&client->dev, "Couldn't turn the display on.\n");
+               goto remap_error;
+       }
+
+       dev_info(&client->dev, "fb%d: %s framebuffer device registered,
using %d bytes of video memory\n", info->node, info->fix.id, vmem_size);
+
+       return 0;
+
+remap_error:
+       unregister_framebuffer(info);
+       pwm_disable(par->pwm);
+fbreg_error:
+       pwm_put(par->pwm);
+pwm_error:
+reset_oled_error:
+       fb_deferred_io_cleanup(info);
+       framebuffer_release(info);
+generic_error:
+       return ret;
+}
+
+static int __devexit ssd1307fb_remove(struct i2c_client *client)
+{
+       struct fb_info *info = i2c_get_clientdata(client);
+       struct ssd1307fb_par *par = info->par;
+       unregister_framebuffer(info);
+       pwm_disable(par->pwm);
+       pwm_put(par->pwm);
+       fb_deferred_io_cleanup(info);
+       framebuffer_release(info);
+
+       return 0;
+}
+
+static const struct i2c_device_id ssd1307fb_i2c_id[] = {
+       { "ssd1307fb", 0 },
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, ssd1307fb_i2c_id);
+
+static const struct of_device_id ssd1307fb_of_match[] = {
+       { .compatible = "solomon,ssd1307fb-i2c" },
+       {},
+};
+MODULE_DEVICE_TABLE(of, ssd1307fb_of_match);
+
+static struct i2c_driver ssd1307fb_driver = {
+       .probe = ssd1307fb_probe,
+       .remove = __devexit_p(ssd1307fb_remove),
+       .id_table = ssd1307fb_i2c_id,
+       .driver = {
+               .name = "ssd1307fb",
+               .of_match_table = of_match_ptr(ssd1307fb_of_match),
+               .owner = THIS_MODULE,
+       },
+};
+
+module_i2c_driver(ssd1307fb_driver);
+
+MODULE_DESCRIPTION("FB driver for the Solomon SSD1307 OLED controler");
+MODULE_AUTHOR("Maxime Ripard [off-list ref]");
+MODULE_LICENSE("GPL");
--
1.7.9.5


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Regards,
-Amar
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